重新订购X，Y数据以定义底部形状

Question

我有定义桥梁开口形状的数据。我已经开发了代码，用一条水平线切开桥的开口，就好像它是水位一样，包括桥墩和墙壁上的交点。我想确保形状始终是边界形状，而不是被切成对角线。当我使用“排序”并绘制数据时，我得到一个Zig Zaw Shape ...所以从另一个过程中获得的Co-ords序列是A，我需要的序列是B ...？如何确保左侧和右侧的垂直点是避免Zig Zaw的序列？

def Plot_Poly(Poly):
    """
    PLOTS THE DATA From the XS Files
    """
    import matplotlib.pyplot as plt

    #============ PLOT ROUTINE FOR CROSS SECTIONS ==============
    print 'About to Plot'
    plt.clf() # Clear any Previous Plots...
    plt.ylabel('Station Elevation (mAHD)')
    plt.xlabel('Station Distance (m)')
    plt.plot([row[0] for row in Poly],[row[1] for row in Poly],marker='o',linestyle='--',dashes=(5,10))  # Plot the Time Series
    plt.show()
    return()


A = [[0,0.95],[0,0],[1,0.95],[1,0.0],[2,0.95],[2,0],[3,0.95],[3,0.0],[4.0,0.95],[4,0],[5,0.95],[5,0.0]]
Plot_Poly(A)
B = [[0,0.95],[0,0],[1,0],[1,0.95],[2,0.95],[2,0],[3,0],[3,0.95],[4.0,0.95],[4,0],[5,0],[5,0.95]]
Plot_Poly(B)